Mini Greenhouses

A mini-greenhouse made from plastic sheeting and wood6 can increase the temperature of the soil and the air surrounding plants and allow you to get an early start on the growing season in the spring and to lengthen the growing season in the autumn. Our design has double-walled construction, which can keep the inside temperature above the freezing point when the outside temperature falls as low as 20°F. This makes the unit a good season-extender for crops.

A mini-greenhouse.

A mini-greenhouse.

KEY WATER FACTORS

The grow biointensive method is especially important for areas with scarce water. Though much more experimentation is needed in this area, the information below should assist you.

Seventy-five percent of the Earth's land surface where food is generally grown receives 10 inches of rainfall or more annually. About one-half of this rainfall can be retained in soil properly prepared for plant use. To grow a good yield, 20 inches of rain are needed annually. In an area receiving only 10 inches of rainfall, the rain a growing area receives can be increased to 20 inches in the "bent bed" examples at the bottom of this page and in the margin on page 80.

The grow biointensive method uses an average of 10 gallons (a 5- to 20-gallon range) per day per 100 square feet while commercial food raising consumes an average of 20 gallons per day for the same area. grow biointensive produces

4 times the food in the same area as commercial agricultural practices.

Research by academic institutions has shown that soil that has living compost as 2% of its volume in the upper 11 inches of soil can reduce the rainfall or irrigation required for poor soils by as much as 75%. (Poor soils have about V2 of 1% living compost in the upper soil area.) grow biointensive encourages maintaining more than 2% compost.

Even under arid conditions, soil that is shaded can reduce evaporation up to 63%, depending on soil type. The minicli-mate created by closely spaced plants provides good shading.

Plants transpire water, which can be reduced by as much as 75% in soils that have sufficient and well balanced nutrients in the soil water. The grow biointensive method prepares the soil so it provides for a high level of fertility.

One way to prepare a 5-by-20-foot "bent bed" for the concentration of rainwater in your growing area.

To conserve water, raise your seedlings in flats until transplanting size (usually for the first 2 to 4 weeks). For many crops, one flat, which needs only about 1/2 gallon of water each day, will plant one 100-square-foot growing area. When planted, this growing area will need about 10 to 20 gallons of water daily during the main growing season. The water savings in one month (compared with direct sowing of seeds in the growing area) is about 285 to 585 gallons of water!

One way to prepare a 5-by-20-foot "bent bed" for the concentration of rainwater in your growing area.

Sloped beds on flat ground (side view) can be used for water harvesting.

Sloped beds on flat ground (side view) can be used for water harvesting.

Native American type of "bent bed" is used to capture rainfall effectively. This is a key water-harvesting technique.

Note

Twenty inches of rainfall over a 4-month growing season is an average of .167 inch per day.

If you combine the last three factors listed above, water consumption can sometimes be reduced to V32 the level (V4 x V2 x ¥4) plants normally require. We have found that grow biointensive can reduce water consumption on average to V8 that of normal methods per pound of vegetable produced and to about V3 that of normal methods per pound of grain produced once the soil is in reasonable shape.

Native people in some parts of Africa have been using a deeply prepared bed approach successfully with grains. They triple-dig(!) the soil, incorporating a lot of organic matter into it just before the seasonal rains. Immediately after the rains stop, they plant their seeds. No more rain falls, yet crops are harvested at the end of the season. others in the area reportedly are unable to grow crops well during this season. grow biointensive techniques should produce at least 4 times the yield under natural rainfall conditions (when not irrigating) that would be obtained under the same conditions with commercial techniques. Let us know what works for you.

Native Americans in the southwestern United States have used a number of approaches to grow food in limited rainfall areas. one method is to create large diamond-shaped growing areas on a slight slope, with one point each being at the top and the bottom of the slope. Crops are planted in the bottom V4 to V2 of each diamond—depending on the amount of rainfall. (More water per unit of soil area is concentrated in the bottom part of the diamond.)

With this method, use the following information to determine how much of the diamond to plant: Well-prepared soil needs to retain approximately 10 inches of water per unit of area (623 gallons per 100 square feet) to grow one complete crop during a 4-month growing season. To retain this much water, the soil needs about 20 inches of rainfall (1,246 gallons per 100 square feet) per season. If only 10 inches fall, you would have only V2 the water needed, and you would plant only the bottom V2 of each diamond. If you had only 5 inches of rain, you would only have V4 the water needed for a crop, and you would only plant the bottom V4 of the diamond (more or less). Experimentation will be required before you have optimum success. Be careful not to overplant. A completely dry soil does not rewet or absorb water easily, which will lead to erosion. To be on the safe side, start with a small area and plant V4 less crop than the above recommendations to ensure that the soil retains some moisture. once you achieve success, you can increase the area under cultivation. Please share your experiences with us and others so this approach can be better understood.

See John A. Widtsoe's Dry Farming (see page 169 in the bibliography) for more information on dry farming.

You Might Just End Up Spending More Time In Planning Your Greenhouse Than Your Home Don’t Blame Us If Your Wife Gets Mad. Don't Be A Conventional Greenhouse Dreamer! Come Out Of The Mould, Build Your Own And Let Your Greenhouse Give A Better Yield Than Any Other In Town! Discover How You Can Start Your Own Greenhouse With Healthier Plants… Anytime Of The Year!